“…Unexpectedly high serum calcium levels occurred in the first three cases tested, and in the light of this we do not feel that the test should be applied to suspected cases of idiopathic hypercalcaemia if fasting calcium levels are greater than 12 mg./100 ml. The exaggerated response to oral calcium may denote hyperabsorption and is presumably part of the basic disturbance in idiopathic hypercalcaemia (Forfar et al, 1956 ;Morgan et al, 1956;Lindquist, 1962). It is consistent with the excess of vitamin-D-like activity found in the serum in some cases (Fellers and Schwartz, 1958 ;Kenny et al, 1963).…”